Air filter



FIG. 1 is a top-front-left perspective view of a first embodiment of an air filter, according to my new design;

FIG. 2 is a bottom-rear-left perspective view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a left side view thereof;

FIG. 7 is a top view thereof;

FIG. 8 is a bottom view thereof;

FIG. 9 is a cross-sectional view thereof, as taken at a line 9--9 shown in FIG. 3 .

FIG. 10 is a top-front-left perspective view of a second embodiment of an air filter, according to my new design;

FIG. 11 is a bottom-rear-left perspective view thereof;

FIG. 12 is a front elevational view thereof;

FIG. 13 is a rear elevational view thereof;

FIG. 14 is a right side view thereof;

FIG. 15 is a left side view thereof;

FIG. 16 is a top view thereof;

FIG. 17 is a bottom view thereof; and,

FIG. 18 is a cross-sectional view thereof, as taken at a line 18-18 shown in FIG. 12 . 

CLAIM The ornamental design for an air filter, as shown and described. 